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Scientists studying microbes that live in volcanic hot springs have invented a way to preserve viruses that could someday change how vaccines are delivered in poor countries.

Much work remains to be done, but an intriguing study in The Journal of Virology describes how Portland State University scientists prevented several viruses from drying out by coating them with silica, the basic ingredient of glass, just as they are coated in hot springs. Once the silica coats were rinsed off, some of the viruses were able to infect cells again.

Most vaccines are made of weakened virus or viral bits, and many need refrigeration. Keeping them cold is a major challenge when it comes to protecting children living in villages without electricity.

“It’s hard to put a fridge on the back of a donkey,” said Kenneth M. Stedman, a biologist at Portland State and the lead author of the study.

By recreating the chemical-laden hot-spring environment, Dr. Stedman’s team coated four types of virus with silica, stored them, then washed off the silica and tried to infect cells. One heavily studied virus, phage T4, which infects the cells of E. coli bacteria, retained 90 percent of its infectivity for almost a month. The virus used in smallpox vaccines also did well, but it is naturally able to be stored dry.

The team is now testing the technique on harder targets: flu virus and rotavirus, which can cause fatal childhood diarrhea. “And we’re definitely interested in polio,” he added.

Coating other viruses and testing them in animals instead of cells will require more work and more grants. Dr. Stedman’s seed money came from NASA, which is interested in how viruses spewed by volcanoes survive in the upper atmosphere.

His team did one animal experiment: It injected the smallpox vaccine virus into mice still in the silica coating. Even then, it touched off their immune systems, suggesting that the body itself may be able to wash off the coating.